The Find A Grave website has Luther Woodruff listed in their database under Rose City Cemetery.
When you get to the home page for Find A Grave, on the right side of the page, under Find Graves, click on "Search 86 million grave records."
In the next screen you can either type in the Memorial number for him, 53037950, or you can type in the first and last name, and year of birth and death if you have them, and choose information about the cemetery location, if you have that, and click search. Find A Grave will look for what you have input. Sometimes if it doesn't find the exact information (name, birth and death dates, etc.) it won't find anything. I usually type in the first and last name, year of death and the location information, at least Country and State. When I find the memorial for the person I want, on the left of the screen there is a place to click to find other persons in the same cemetery with that surname. Click on that link and it will pull up a list for you.
You can also look up the name of a cemetery by doing a cemetery search. You can also look for a cemetery in a state and county. You can also search for the names of all the cemeteries in a specific state and county by not including any cemetery name. The list will provide the name of the cemeteries with the city or town name to help you find cemeteries where your person lived and in which they may be buried. Please note that Find A Grave information is posted by volunteers, and not all cemeteries are listed as yet and not all persons in those cemeteries are listed. If you find a person you want and they don't have a photo of the gravestone, you can request a photo. There may or may not be a gravestone for that person, but you can ask for a photo and see what happens.
Every webpage for each person will have a "Memorial" number at the bottom. It also gives the name of the person, or group that created the information or manages that memorial. If you click on the name of that person, or group, the link will take you to them and usually a way to contact or leave them a message.
I entered Luther Woodruff, Year of death, chose United States, Oregon and Multnomah County and clicked Search. The following came up on the next page:
Woodruff, Luther W. b. Mar. 31, 1870 d. Aug. 8, 1913 Rose City Cemetery Portland, Multnomah County, Oregon, USA
I clicked on his name and the memorial page came up.
His memorial number was: 53037950
There is information posted to the memorial page regarding this family. It includes the name Julie Mendenhall, Agnes Marie Woodruff, Laura and Freida. prudence J Martin Woodruff Crawford Scheble, James Blackburn.
There is a photo of the gravestone on the memorial number with the following information. (If you click on the picture the next page will be larger and sometimes easier to read.): "Mother Prudence J Scheble, 1848-1919 Her Son Luther W. Woodruff, 1866-1913"